Improve tests and unify required attribute

freqtrade/constants.py

@@ -269,10 +269,8 @@ CONF_SCHEMA = {
             'required': ['process_throttle_secs', 'allowed_risk', 'capital_available_percentage']
         }
     },
-    'anyOf': [
-        {'required': ['exchange']}
-    ],
     'required': [
+        'exchange',
         'max_open_trades',
         'stake_currency',
         'stake_amount',

tests/test_configuration.py

@@ -40,10 +40,16 @@ def test_load_config_invalid_pair(default_conf) -> None:
 
 
 def test_load_config_missing_attributes(default_conf) -> None:
-    default_conf.pop('exchange')
+    conf = deepcopy(default_conf)
+    conf.pop('exchange')
 
     with pytest.raises(ValidationError, match=r".*'exchange' is a required property.*"):
-        validate_config_schema(default_conf)
+        validate_config_schema(conf)
+
+    conf = deepcopy(default_conf)
+    conf.pop('stake_currency')
+    with pytest.raises(ValidationError, match=r".*'stake_currency' is a required property.*"):
+        validate_config_schema(conf)
 
 
 def test_load_config_incorrect_stake_amount(default_conf) -> None: